Comtech EF Data DT-4500 Series - Manual (Page 77)

DT4500 Series Down Converters MN/DT4500.IOM
Remote Control Revision 1
59
B.3 A
CCESS
M
ETHODS
Converters may be accessed directly by using a physical address or indirectly through a
backup Converter by using a virtual address.
B.3.1 D
IRECT
A
CCESS
Converters may be directly accessed by the RS-232C interface or by the RS-485 interface
in a bus configuration.
B.3.1.1 RS-485
In this control network, all converters including the backup Converter are paralleled on a
common RS-485 cable. Both up and down converters can be mixed on the cable as long
as each converter has a unique physical address. Only one RS-485 port is required on the
system's monitor and control computer. If a change is initiated directly to a converter in a
redundancy subsystem, the backup Converter will detect the change via the High Speed
Bus and update its backup tables.
B.3.1.2 RS-232
For RS-232 control, a direct RS-232 cable connection is made to each converter to be
accessed. If an external Monitor and Control Computer is used, one RS-232 port per
converter is required. This mode is commonly used with an ASCII terminal for bench
testing.
B.3.2 I
NDIRECT
A
CCESS
Converters in Redundancy Mode may be addressed indirectly by adding a virtual address
to the backup Converter's physical address. The virtual address corresponds to
converter's position in the redundant subsystem. The backup Converter recognizes the
virtual address and executes the command via the high-speed bus.
B.3.2.1 RS-485
To control by using the RS-485 interface, one or more backup Converters are connected
to a system's monitor and control computer or ASCII terminal with a common RS-485
bus cable. Both up and down backup Converters may be mixed on the cable as long as
each has a unique device address. In order to indirectly address an online converter in the
subsystem, a virtual address must be provided. The virtual address corresponds to the
converter's position in the chain beginning with number 1. Virtual addressing is only
recognized by a backup Converter. Only one RS-485 port is required on the monitor and
control computer.